Leveraging CircleCI API to include build logs in Slack notifications
The Slack Orb allows you to send notifications, and customize the message sent. In most cases, this is used to indicate a build status, such as if it failed.
While the above is helpful, it still requires you to navigate back to the build to get information about why it failed.
Wouldn’t it be nice if you could include the last few lines of the log output with your Slack message? This could help easily identify the issue, such as the exit code reason or specific error messages. Maybe something like this…
The following guide will provide step by step details on setting this up!
Requirements
- This guide utilizes Orbs, so you will need to be on at least version
2.1. - The API calls and data manipulation are done in bash so your image will need to support that (including utilizing
jq). - While this should work out of the box, you may need to adjust slightly to account for how your steps output values.
Setup the Slack orb
Information on setting up the Slack orb.
Once the above is done you will need to ensure you include it within your config.yml file with the following:
orbs:
slack: circleci/slack@4.2.1
Configure Environment Variables
Both the Slack orb and the run steps contained in this guide require some environment variables to be set. These can be done at the project level, or, if you plan to use it across projects – set these up in a context.
| Variable Name | Description |
|---|---|
| CIRCLE_API_TOKEN | This will be a personal API token. |
| SLACK_ACCESS_TOKEN | The OAuth token acquired through the Slack setup steps. |
| SLACK_DEFAULT_CHANNEL | If no channel ID is specified, the Slack orb will attempt to post here. |
The SLACK_ACCESS_TOKEN and SLACK_DEFAULT_CHANNEL should already be set from following the “Setup the Slack orb” step above.
Add the run step that collects and prepares log data
The snippet below should be able to be added as one of the last steps in the job you want to be notified in. While you can copy and paste it, you may want to adjust some parts.
- Remove or adjust
jqinstall lines accordingly (first two steps undercommand). If you already have it installed on the image, remove them. If utilizing an alpine image, adjust toapk. - On line 9 of the
commandstep, adjust the amount of rows from the log you want returned. It’s set to 10,tail -n 10, so adjust10accordingly.
- run:
when: on_fail
name: Generate last log lines for slack message
command: |
sudo apt-get update
sudo apt-get install jq
API_URL=$(echo $CIRCLE_BUILD_URL | cut -d/ -f4-7)
FAILED_STEP=$(curl "https://circleci.com/api/v1.1/project/${API_URL}?circle-token=${CIRCLE_API_TOKEN}" | jq '.steps | .[] | flatten | map(select(.status? == "failed")) | .[] | {allocation_id, step}')
ALLOCATION_ID=$(echo "${FAILED_STEP}" | jq -r '.allocation_id')
STEP=$(echo "${FAILED_STEP}" | jq -r '.step')
curl -o slack_response.txt "https://circleci.com/api/v1.1/project/${API_URL}/output/${STEP}/0?file=true&allocation-id=${ALLOCATION_ID}&circle-token=$CIRCLE_API_TOKEN"
sed -i 's/\r$//g' slack_response.txt
SLACK_MESSAGE=$(cat slack_response.txt | tail -n 10 | sed '$!s/$/\\n/' | tr -d '\n')
echo $SLACK_MESSAGE
echo "export SLACK_MESSAGE='${SLACK_MESSAGE}'" >> $BASH_ENV
Invoke the Slack orb and utilize the message generated
The below step should go right after the above step. You can adjust as needed, but you will likely want to keep the following block:
{
"type": "section",
"text": {
"type": "mrkdwn",
"text": "```${SLACK_MESSAGE}```"
}
}
As the above ensures the log message is included in the Slack message. Add this below the “Generate last log lines for slack message” step that you added in the last section.
- slack/notify:
event: fail
custom: |
{
"blocks": [
{
"type": "section",
"text": {
"type": "mrkdwn",
"text": "```${SLACK_MESSAGE}```"
}
},
{
"type": "section",
"text": {
"type": "mrkdwn",
"text": "Build failed, above is last few lines of the log"
},
"accessory": {
"type": "button",
"text": {
"type": "plain_text",
"text": "Click Me",
"emoji": true
},
"value": "click_me_123",
"url": "${CIRCLE_BUILD_URL}",
"action_id": "button-action"
}
}
]
}
That’s it! You should now receive the last few log lines of the failed step as part of your Slack notification.
Resources
This guide stemmed from a previous solution I provided a customer, which was a bash script that did something similar.
If helpful to see how this would look in a config.yml see the following gist: